The news follows the release of the latest capital plan, which outlines funding for the next 15 years across all areas of council provision.
Portlethen Primary is omitted entirely from the document and the authority says that declining rolls at the school mean replacement is no longer "deemed necessary".
However, in 2005 it featured on a list of 22 "priority" schools and at the January meeting of Portlethen Community Council Thelma Birnie, head of schools for South Aberdeenshire, assured members the school "would not be forgotten about."
They were told that under the Fit For Purpose Criteria, Fishermoss is currently in the 'C' bracket, while Portlethen Primary is listed in the 'D' range – the lowest score possible.
Members said they were disappointed by the move and would be seeking clarification on how the decision was reached.
Councillor Alistair Bews said: "We were told a new school to replace Portlethen would be built on the existing site but it appears clear from the document that is not going to happen in the next five years.
"Portlethen has been unfit for purpose for years and I don't see it can wait that long."
Community council member Ricky Skinner said: "They seem to be using the new Hillside School as an excuse.
"We were told Portlethen would be a three primary school town and all of the school buildings should be up to standard."
In a statement to the Leader, Aberdeenshire Council said: "With the new housing development at Hillside it is anticipated that the population in the area will increase by a significant amount, hence the reason a new school in the area has been identified within the capital plan.
"In comparison, the roll at Portlethen Primary School is in decline, and with the school well within its capacity limits, the need to replace the school is not deemed necessary at this time.
"Portlethen Primary School is in good condition and well maintained, a point which was highlighted in the schools last HMIe report."